1. Field of the Invention
This invention relates generally to the use of electrosurgical methods and apparatuses for the treatment of damaged tissues and, more particularly, to the treatment of disrupted articular cartilage in the joint of a mammalian body.
2. Description of Related Art
The normal function of joints in humans depends on the distribution of relatively large forces across the body surfaces. In diarthrodial joints, the magnitude of the joint forces reaches levels four to seven times body weight. These forces are dispersed by articular cartilage in the joint. Proper cartilage function occurs via a highly organized extracellular matrix maintaining a fixed charge density and possessing a high affinity for water.
Chondromalacia occurs when cartilage beds in joints become worn and degenerate into strands of cartilage which extend away from their respective cartilage beds and into the joint cavity. The cartilage surface becomes visibly disrupted, fissured and fibrillated. The damaged cartilage has deleterious effects on the mechanical properties and normal function of articular surface. The fibrillated cartilage may break down and break off to form particulate matter. It is the particulate matter (broken fibrils) and various proteins and enzymes released when the normally smooth layered architecture of cartilage is undermined and frayed, which causes pain by irritating the synovial lining of the joint.
Treatment to date has included surgical intervention. In one arthroscopic procedure, a shaver is introduced through an arthroscope and is used to mechanically remove the strands of disrupted and fibrillated cartilage. However, this treatment can disrupt and remove part of the normal healthy cartilage bed and does not restore a smooth surface nor improve the mechanical function. Another modality for the repair and treatment of the damaged cartilage includes open procedures which can lead to increased recovery time and a possible increase in pain and further dysfunction of the joint.
Another exemplary device for treating fibrillated cartilage joint surfaces or irregular cartilage joint surfaces in an arthroscopic procedure delivers sufficient thermal energy to reduce the level of fibrillation of the cartilage joint surface. See U.S. Pat. No. 6,068,628 to Fanton et al. Particular care is used to minimize any undesired thermal effect on non-targeted tissue and thereby prevent necrosis below the surface of the cartilage joint surface into the healthy layer since cartilage does not grow and regenerate after being damaged. In view of the foregoing, it would be desirable to provide a thermal treatment device to coagulate the fibrillated cartilage strands together and closely monitor the ambient temperature in the immediate or surgical environment of the fibrillated cartilage so as to minimize undesirable cartilage damage and necrosis of underlying subchondral bone.
An apparatus for treating disrupted articular cartilage comprising an elongate probe member having proximal and distal extremities and a handle coupled to the proximal extremity of the elongate probe member is provided. The distal extremity has a peripheral wall defining a cavity and a distal opening communicating with the cavity. A controllable environment is created within the cavity when the distal extremity is placed substantially flush against the disrupted articular cartilage. An electrode is positioned within the cavity at a distance spaced inwardly of the distal opening. The disrupted articular cartilage is sealed to form a substantially continuous surface when energy is supplied to the electrode. A method of using the apparatus is provided.
In general, one advantage of the present invention is to provide a minimally invasive apparatus for delivering energy within a controllable environment to articular cartilage and particularly fibrillated articular cartilage, for treatment thereof, while minimizing collateral thermal effect on non-targeted tissue.
A further advantage of the present invention is to provide an electrosurgical probe which can more accurately monitor temperature of articular cartilage being treated within a controllable environment for a more precise feedback control of thermal energy delivered to tissue.
Another advantage of the present invention is to provide an apparatus of the above character in which sufficient thermal energy can be delivered to coagulate cartilage fibrils in predictable and reproducible levels thereby minimizing collateral damage.
Yet another advantage of the present invention is to provide an apparatus of the above character which can be used for treating chondromalacia and other articular cartilage defects.
The accompanying drawings, which are incorporated in, and form a part of this specification, illustrate embodiments of the invention and, together with the following description, serve to explain the principles of the invention.